Mini cooper sidewalk convertible 2007?

Hi I've got a problem with my sidewalk mini I can't lock the doors with my keys tried both nothing is happening when I start the car they automatically lock inside took it to my local garage he printed off reasons tried it by holding the key fob down managed to lock and open it next day opened it and it happened again can't lock my car. Had this car 18 months have had no end of problems with it love my mini but seriously not considering buying another is there any thing you think I could try to re programme the keys again ????