Since this wasn't done by the builder but another pool service company, you can try complaining to them. Given that is the type of work they do they probably won't respond well. That is one of the worst installations I have ever seen.
Are you removing the heater in the winter? If not, why is it powered through an extension cord? You don't get anywhere near the amount of flow through flex pipe as you do rigid for the same diameter. Cutting that flex pipe out, Putting a 2.5" coupler over the heater fittings, putting a 2"-2.5" reducer bushing in the other end and replumbing would be best. Then change to 2" plumbing. Change the pump outlet plumbing as well.
Are you removing the heater in the winter? If not, why is it powered through an extension cord? You don't get anywhere near the amount of flow through flex pipe as you do rigid for the same diameter. Cutting that flex pipe out, Putting a 2.5" coupler over the heater fittings, putting a 2"-2.5" reducer bushing in the other end and replumbing would be best. Then change to 2" plumbing. Change the pump outlet plumbing as well.