how can i open the door?

hi,

i have a hotpoint aquarius 1100 washing machine and the door light won't go off. we cannot open the door at all. we keep doing different wash and dryprogrammes but the light will not go off. we have tried unplugging the machine. please can you advise best/cheapest way to fix it. we have no guarantee as we just moved into a new house and this is what we were left with. the first three or four washes were fine and then the door wouldn't open