Parents across Warwickshire were made to pay to receive letters from the county council as they were accidentally sent without postage.
Many people across the county were told they needed to pay £2 for a letter to find out it was Warwickshire County Council reminding them to renew school transport.
The council said it was caused by an error by its mail supplier and will be refunding all those affected.
Eastlands councillor at Rugby Borough Council Dale Keeling said many parents are not pleased they have had to pay and will be seeking reassurances this will not happen again.
“I’m a borough councillor and I’ve had to explain to people why the county council are sending these letters without postage,” he said.
“I imagine it was a one-off mistake but parents have been asking me because they have gone through all the hassle of collecting the letter, thinking it was a gift or something and getting quite excited, but to find out it’s from the school they weren’t too pleased.”
Cllr Keeling added he was told Post Office staff have had at least 150 of these letters, which were sent on May 26, two weeks before it arrived on Thursday (June 8).
A Warwickshire County Council spokesman said: “Unfortunately, due to an error at the Rugby offices of our franked mail supplier, a number of letters from Warwickshire County Council went into the Royal Mail system without any postage.
“Warwickshire County Council is committed that it will be reducing transport costs by £2 or administering refunds over the phone by card to any families affected and would like to apologise unreservedly for any inconvenience caused.
“Any families affected by this are urged to email Education Transport, email@example.com, or call 01926 412929 (Option 1, Option 1) to arrange for remedy to be made.”