Poor service provider and poor after sales service within warranty period

For quite a few years now we installed Kwikot cylinders for clients. With a so-called 5 year warranty. The cylinder itself we have little problems within the warranty period time. In other words, the cylinders usually burst only about 5 to 6 years after installation, sometimes later. But for the first time we have a cylinder that burst within the first 3 years. No problem for the cylinder has a 5 year warranty, right? It's fast and easy to register a claim, but oh my word!!! Exactly 1 week later after we had to phone them once again, they realized that the so-called service provider JAK Loodgieters didn't answer the phone for 5 days already. In the event my business' name is linked to this very bad service. When a geyser burst it is always seen as a matter of urgency. But exactly one week later and our client haven't received a phone call from the co-called service provider...? I am sorry, but if you can not deliver a service, you surely can not be a service provider!!! Kwikot!! Please look at your service providers! We need your help to help our clients!!