ASK travellers what is likely to cause them to fly off the handle and many will point to those 'pie in the sky' advertisements promoting amazingly cheap airline tickets.

Take two different ads for flights to Bangkok. The one for Singapore Airlines cites an airfare of $308 while the other, a Thai Airways ad, offers a $140 ticket.

It looks like a no-brainer, but add up the costs reflected in the small print of the Thai Airways ad - those various surcharges and taxes - and the $140 ticket suddenly balloons to $300, just $8 cheaper than SIA's.

The extras can also turn a budget airline's advertised price of, say, $19.99 into a ticket costing up to $200.

The irritation these ads cause led SIA to promise last week that it will now state full fares so travellers will know at a glance how much a trip will cost.

But airlines are not the only offenders.

Travel agencies are also prone to flights of fancy on prices.

The Consumers Association of Singapore (Case) received 838 travel-related complaints in the first 11 months of this year, of which 23 complaints were from travellers angry about having to pay more than the advertised price.

The Advertising Standards Authority of Singapore (ASAS) also received six complaints on incomplete or inconsistent prices on travel ads.

A typical ad will read: Four days, three nights in Hong Kong, from $588 - but no fine print stating that taxes are not included.

When The Sunday Times visited the agency at People's Park Centre which offered the $588 package to ask about it, the actual cost came to $897 after taxes and additional costs for airfare.

At People's Park Centre, a major travel agency hub, ads quoting attractively low prices for tickets and travel packages line the doors of every agency.

But when customers inquire about the offers, agencies say the prices don't include taxes or are for early birds only. Most people end up with a price of up to $350 more.

Secretary Rachel Wong, 36, learnt the hard way that the prices quoted on such ads are not to be trusted when a package to Japan advertised at $1,700 ended up costing her $2,100.

'The taxes weren't included. I had to pay $120 more because there weren't enough seats and I also had to pay for my own tickets to Tokyo Disneyland,' she said.

Agencies told The Sunday Times it is hard to advertise full rates because airline surcharges and government taxes fluctuate regularly.

SA Tours spokesman Ruth Lim said: 'If we publish full rates and the airline suddenly ups its surcharge, customers will hold us to the published rates and it would be unfair for us to bear the additional charges.'

However, some agencies admit that they put up vague ads with low prices just to draw consumers.

One agency had an ad that read: Krabi from $130. But airfares were not included and the $130 covered only a two-night hotel stay. A full package cost $287.

Ho Wah Travel executive director Steven Tan said agencies sometimes advertise rates of only land tours, excluding airfares, to make prices seem more attractive.

'The lower the advertised fare, the higher the chance that customers will call you instead of another agency,' he said. 'When they call up, we then explain the extras.'

The chief executive of the National Association of Travel Agents Singapore (Natas), Mr Robert Khoo, said agencies that are not upfront about prices are 'unethical' and that consumers should boycott them.

But most agencies said stiff competition made it hard for them to be upfront.

Mr Keith Leung from Travel Unlimited said: 'If we put up full rates and the other agencies don't, no one will come into our shop.'

ASAS chairman Eleanor Wong said airlines and travel agencies should advertise full rates for greater transparency. She said: 'We encourage consumers to choose companies which do so, as this will put pressure on those who do not advertise full rates.'

Private tutor Tan Kok Sheng, 33, now double- checks what a tour package includes before paying.

'As long as I haven't paid, I have the power to get out of an unfair deal,' he said.

mavistoh@sph.com.sg