Hi,how can I fix my Hotpoint Aquarius WD420 please?

HI, I have a problem with my Hotpoint washer/dryer. Everytime I switch it on, the program starts ok. Then, within two minutes, during filling, the pump starts sending the water back out the waste pipe again. This is accompanied by flashing lights('on/off'- quickly & 'crease hold'- slowly), pause of program & a full lock out of all buttons. This happens with ALL programs & can only be stopped by pulling the plug. Please help, as I have a mountain of washing and cannot afford a repair man- Thank you for any help you can give me. Liz