Major problem. Connected up new rear lights. However Iv suddenly got a reverse action. Brake lights constantly on but when I press the brake pedal it goes off. WTF!!!! Any ideas???

Edit: Ok all other lights, hazards, fogs, beams all working except the poxy brake light. Still constantly on and off when you press pedal. HHHEEELLLLPPPPP!!!!!!!!!!

Iv changed the brake light switch to a new one. Seated it properly and its still on. Im started to get f*cked off now coz i can see im going to have to take it to the sparky for them to charge me a stupid amount of doe. Any ideas please guys. Im desperate.