Fit for purpose

I purchased a Kalkhoff in August 2018. I have ridden about 10,000 miles on it. It is hard to say exactly how far I have ridden it since the display unit has failed and been replaced 3 times - and this has been the start of my problems. I've had 3 battery fails, one motor fail, two control switch fails and as a result the bike has been unusable for about 15% of the time I have owned it. Up to now, the retailer has grudgingly replaced parts under warranty but now, just outside warranty, the battery has failed again and the quote is £700 to repair.

My feeling is that the bike is just not fit for the purpose I purchased it for - to ride regularly in mixed Scottish weather.

The retailer accuses me of "tearing out" the cables from the display unit, whereas actually what happens is that the cables are under stress because of the angles they are forced through and therefore split. The retailer also says I have damaged the bike by transporting it unprotected on the back of my motorhome. With the greatest respect to any motorhomers, I wouldn't be seen dead in a motorhome and on the few occasions I have transported the bike on a rack on my van it has been fully protected - Fiamma cover plus old waterproof clothing around the parts I would consider to be vulnerable to water ingress.

Does anyone have similar experience of failures on a Kalkhoff Endeavour using the Impulse system? Does anyone have any experience of successfully arguing a case of "not fit for purpose" under the Consumer Rights Act?

Any help or advice welcomed. Happily just received my new Ribble