I have done mine at Regal Valet and they are professional and provide good after sales service. They are always willing to help if you have any issue after the coating.

But bear in mind, actually whatever coating also need maintenance or good taking care even though they provide the 4 or 5 years warranty. I don't think there is any coating can survive permanent. Especially coating can not prevent water spot. This is just my research after done some online browsing. 

I done mine(M4 package) since august till now. Actually I went back twice to ask them settle some issue for me and they are willing to help without charges. I am not sure the partial recoating free service. For RV, they do apply back the coating for the area for free if polish work is required. at least I went through this twice. Can say most of the time they are willing to help.
And they have a activcare session(cost around RM500) for the outside and interior maintenance which include remove the swirl marks, light scratches and reapply the coating again if not mistaken. I think you will only need to do this if you have serious swirl or scratches issue on your car after apply the coating. RV is using GYEON(korean) product, can online do some research on the products.
My friend has done coating for few cars by RV and the result are quite good. I can see one of his car still looks shinny after 3 years.

However, this is just my experience with RV. Ceramic Pro is quite famous also and can see a lot peoples are using them. Maybe you can get some feedback from any of them first.

Found this:
https://www.youtube.com/watch?v=V1ykNBdQK9A


Btw, what car you are planning to coat?