Don't worry about it, you put the correct account number on the payment and the Council's payment system will allocate it to the correct account number. If the payment system cannot allocate it to the correct account then it goes into the suspense account along with many other payments that the Council will receive, the council income staff are very well versed on sifting through the suspense account to track errant payments. When you made the payment did you receive a confimation email with a payment reference number and time of payment?
One local wag near me sends payments with the payment reference as 'Council Wankers', his payments always reach the correct account.