Renault clio problems, problems?

My sons car has just cost £200 to get through its MOT the sun roof has been leaking a while now and the front seats are stained as a result of always getting wet - is there a way to fix this? also does this contribute to....

Car won't start at all now always been a bit hit and miss but nothing now just a little flashing red light....

The central locking hasn't been working for a while now and we were down to 1 key working but now the little red light constantly flashes and the car won't start, my husband tried the battery etc so now...

we have no radio code to restart the radio!!

Any help on all these problems would be wonderful. Thank you in anticipation.