Under Ofcom regulations, the speed advertised should be the estimated speed you are likely to experience at busy times of the day which tends to be between 8-10pm.
Your Internet Service Provider (ISP) should provide a minimum guaranteed speed for your broadband service.
If you do not get the speed that you were promised, get in touch with your ISP and give them the opportunity to resolve the problem.
If they can’t fix the problem within 30 days, they must allow you leave your contract without being penalised.