No, it won't. You will still be at the contract rate unless you leave and go to a different provider or sign a new contract with the same company.
It's an excellent time for bargaining with your company if you want a better tariff (than advertised) or supremo upgrade. They positiviely won't want to lose you. Some companies even have a "we'll match your best contract offer so far" type deal.
Have a look at the fantastic Martin Lewis's site www.moneysavingexpert.com for all sorts of tips about mobile phone contracts (and much more!).
Good luck
221b