SINGAPORE - The founders of online supermarket RedMart have apologised to its customers for its "significant service problems".

The Singapore start-up had to cancel or delay several orders between Feb 25 and 28, and even now customers can only choose from very limited delivery slots for their groceries.

Acknowledging that the problems caused "a lot of difficulties and frustration", the founders Mr Roger Egan, Mr Vikram Rupani and Mr Rajesh Lingappa said in an email to customers that the cause was the firm's transition to a new warehouse.

"We'd like to apologise and explain what we're doing to resolve the problems," they said. "On behalf of RedMart, we are truly sorry for not delivering on our promise of a convenient and great shopping experience. We will fix things immediately and hope that you will give us the opportunity to serve you again."

The trio said they are hiring more customer support staff and revising the process for cancelled or incomplete orders so payments are automatically refunded instead of account credits being issued.

However the apology did not mollify all customers.

Ms Yvonne Chee posted on the RedMart Facebook page: "My experience... was so horrible that I'm not sure if I will want to order again."

Ms Elaine Woo wrote: "As a regular of RedMart, I applaud this sincere apology and explanation. People just need to be a tad more flexible and understanding."