KSD Gas

My boiler provided lukewarm water in November 2018. -He misdiagnosed the problem 4 times and charged me for that on purpose. -He misled me to buy 3 parts in working condition -He overcharged labor rates as his own while -He illegally sent an unqualified plumber to do the job which directly results in the failure after only 9 month, while my original heat exchanger lasts for more than 6 years. -He charged me for the pump and his labor for £280.00 on his invoice while he told me it will cost only £220.00 after his first inspection. - on invoices, he did not charge for the sensor and the filter, but clearly, he added it to the costs for the pump and heat exchanger instead and told me he did not charge for the sensor and filter. -He never provided the purchase invoices and payment confirmations for all the parts that he ordered for me as pre agreed. - He charged me £950.00 for replacing a part only in fact. -I have to pay 4 extra trips and £100 compensation to tenants