My tvs ki mobility solutions private limited - GST and tax Avoidance

I've used myvts for my car periodic maintenance service.they have sent me a bill of Rs **,*** for some parts replacement which i declined and asked for normal service only .some time later they send me a preinvoice and asked me to pay Rs **** before the delivery of my vehicle and declined to send my car without that i've paid that amount however they have not yet provided final bill for this servicing and upon receiving my car i realized that my car was not serviced.there is no water wash or cleaning done and it was full with dirt.it seems they are avoiding taxes by not sharing the invoice to the customers. thanks Nitin