Dealer Problem

Hi

Im new to road cycling and brought myself a Ribble sportive 7005 road bike to see how i got on.
The bike was great until I brought a pair of Continental 4 season tires.
the front was fine but the rear when inflated to correct pressure rubbed on the front mech bracket so much that the wheel would not turn.
I called Ribble and after lots of tooing and throwing with pictures they agreed that there was a problem with the frame and that they would replace it at there expence.The bike went back and after 3 weeks was returned and as a good will gesture they gave me a £2.99 water bottle.
I fitted the new tires back on and the rear tire was so close to touching the front mech with proberly only 1mm clerance but it seems ok.
Everything was fine untill my second ride was 30 miles away from home climbing a steep hill when the left crank arm shered off the holotech bb,striping the splines off and making it difficult to get it to stay on.
I emailed Ribble on monday tuesday wednesday and have had no reply when i called and i was fobbed off and no return call,I have told them that I will seek legal advise but there not interested.They were so quick to take my money and get me the bike but now theres another problem they are not bothered Im so annoyed with there customer service I dont know what else to do I need to get a new crank fitted as im worried it will come off again ,has any one else had bad dealings with ribble I certainly wont be using them again.
Ian