Axxess VOIP - NOPE

We had a great experience in getting fixed LTE through Axxess. We then decided to get VOIP through them as well. Big mistake! Their preconfigured phones are out of stock, and they can't say when they will be back in stock. They assured me that getting a Yealink phone from an independent shop would be fine and I checked if I could get the W53 model. They said it would be compatible and easy to set up. I went ahead and bought the phone elsewhere. Trying to set it up with Axxess tech on the line was a nightmare - it took hours and in the end did not succeed. I was then told that Axxess doesn't support the W53 model and there was nothing they could do to help me and I should return it if I can. I called again after about an hour to confirm this, and spoke to a different agent who told me something completely different. She said Axxess definitely does support this model of Yealink and that the ping process was not completed during my setup. I should try again. Now, what must I believe? Must I try to return the phone to the shop, get another model, or pay a private IT person to try and complete the setup process on my behalf? Should I just s**** my new VOIP account and look for a different provider? Does Axxess even know what it can and can't do? My impression is that they are great for LTE but have not mastered VOIP at all.