megane electrical

Hi I have a 4yr old Renault Megane which a bought a year ago has been running fine until the last month when the locks would only off the remote when they felt like it, when finally got in car and put the card in no lights on dash and would not start, so went back in house to tell the wife went back outside and guess wot everything was fine this got worse over the next week so took it to Renault main dealer and they said it was card reader so orderd new card reader and cards at a cost of £600. Got the car back and the problem is still there went back to Renault who have now said they don't no whats wrong as the problem is intermtent

Hope someone can help only pulling my hair out

Thanks

Steve