Speed Motorcycles

My motorcycle needed the MOT done.
I left it at the venue and got a watsup message informing me it needed the front Mudgard and Wheel replaced for 65 and 70 quid respectively. They offered me a second hand mudgard in dark blue and asked if I wanted it painted. I responded it was all right to have it in a different colour because I didn’t want to pay even more.
The next day when I get in person to the shop I was informed that the wheel was not replaced it was not actually needed or something. (?) and that he had replaced my mudgard for a brand new one. (Which needed to be painted too…) and they would charge me only 100 quid. The excuse is that he was so nice and my friend so he decided to do that.
Being only one day since we had spoken via watsup I had my own mudgard which I wanted to use instead. I would have paid for the wheel and some installation fee for my own spare part and I came to consult with them if it was possible. When I mentioned it the owner of the shop started to speak loud. Give me “life lessons”, patronise me and humiliate me in front of everyone and kindly suggested that I would take the spare part I had purchased and shove it up.. you may imagine where.
I called off the disrespect and asked politely to be treated with proper vocabulary. I did not loose my temper or raised my voice to this gentleman at any point. I was actually scared I would even to be physically assaulted if I did. As a result he took my spare part and carried it to the back of the shop. Basically seized it. And told me I should be thankful he worked to make my bike really.nice. Making a long story short; I end up having to cope with a service/product I was not consulted about. Tolerating this gentleman to make decisions on my behaviour; insulting and patronising me; seizing my spare part. Telling me that I had the option of him to remove the Mudgard (the one he decided to install without my permission) and install the one I purchased for 90£. As he specified 45£ for the one he installed (again by his own grace) and 45 more to install mine.
So misleading and I was so overwhelmed by the absurdity of this situation that I left the shop after being informed that I should pay 60 quid to take my bike and leave the spare part I purchased for them.
They only answered my query on watsup later on asking me what I wanted. The employee who witnessed everything was very embarrassed by his boss behaviour. To the point I felt sorry for him (such a nice down to earth person).
Not happy enough the owner went on with his performance playing a victim who was just trying to help me and that I would never be welcomed in his shop again. As per other reviews I have read here this must be an usual practise of performing unwanted help and charging you arbitrarily for that afterwards without any notice. My bike is still at the shop and I ask myself if I can put my safety in their hands to ride it after such unacceptable and irrational behaviour of the owner of the business. I will leave this question for you to answer.