Can you please recommend a reliable vendor for registering WEEE in DE?

We started with Bellacocool more than 6 months ago and till today our sales are still frozen. They've changed the category we wanted to register to another one (they thought was better) and as a result Amazon is not accepting our products within this category. The registration cost us a lot and even worse it cost us 6 months of delay for introducing the products to the market. Communication is very poor but in their opinion, it's not their problem and they suggest that we simply pay them for a new category which is ridiculous. Have you had issues like this with other suppliers?

Best