People have asked about the price. Did you supply ALL materials used on site except odd bit of pipework, screws, and perhaps some silicone sealant? Was there a written quotation or was the whole thing verbal? Most importantly: are you house or a flat, which town, and is there free parking directly outside?
Regardless of price, however, in the context of the overall project, I think a customer would reasonably expect an 'upgrade' to a towel rail to not have plastic pipe draped across at an angle (asymetrically, at that). I cannot think of many people who would want it as you have it and I personally would only have left it like that if that was clearly what we had agreed.
What I don't understand is why no mention was made of repainting or lack of it - this is the only bit that makes me wonder whether there was not a breakdown in communication that left the plumber thinking you were going to carry out work on the wall at a later state and therefore the towel rail installation is a bit temporary.