You need to ring Trading standards first before you do anything else and advise them of the faults and they will give you a case reference number and advise you of your rights , which is basically a vehicle not fit for purpose, then go after the sellor as he is a trader knowing your rights, you can force them to repair faults , be warned thow they may just fix as cheaply as possible, bodge stuff up so check carefully if they do repairs that they are suffiiant and correctly repaired , or youl be intitled to a full refund, advise the sellor trading standards are involved and he will bend over backwards to make you happy as he knows this means trouble for him if they do get fully involved, if no joy from the sellor as his small print says sold as seen which means nout in the eyes of the law and trading standards go back to trading standards as they will get more involved if the sellor wont fix the problems or give you a full refund