had a similar experience with mail order parts , with Nippon Spares in London, wouldnt refund my credit card for none arrival of goods ,despite several phone calls etc.
First contact credit card Co, they will send dispute form, then to really stir things up contact your local trading standards office and tell them the company has breached distance selling rules.. I found that this really got things going and they sorted a refund within 2 hours of trading standards contacting them They eventually got took to court on other matters arising from it as well, May help
the car goes up to 130 with no problem at all then it struggles on up to 150 and wont go any faster, yes i know that is still fast but it is limmited to 155 and nissan admit it should not be too sluggish and should do 155 great car thou.
is the car all standard (exhaust , inlet etc. ) ?