Just had a thought - if you are in fact the owner of a property that you rent out then you are responsible for maintenance, but you should be free to choose the services of any available licensed maintenance operator. Note that if you have signed up to an insurance scheme to which you have been paying then by changing before the check is due you in effect throw away some payments - but the way you put it, the company in question is simply assuming you will use them as before with a one-off payment (in effect "bouncing" you into a job and a bill for it unless you tell them No Thanks in time).