Sorry for your experience but
@rvitko is the best source of product information and support for Tunze. I do recommend using Tunze products for the internal filter as they are designed to work specifically with their filter housings. PM me if you get stuck with the filter from BRS. I might be able to help you. I use both Tunze and Eheim and believe in them both due to the many years of trouble free service they have given me and my old costumers in the aquarium industry.
Don't give up yet you are still to young in the hobby for that! It is a hobby so structure your expenses according to your ability to experiment and grow. Equipment does not make the hobby grow the hobbiest does! Take care of the animals first and learn their needs. Some of the best aquariums I have ever seen were very simple and stocked on the lighter side. Example would be two clown fish in an anemone with shop lights and macro algae in a 50 to 70 gallon tank with undergravel filters driven by air pumps. The guy had a dozen tanks with various species of clowns and he was breeding them for fun. The salt spray from the air stones was a mess but the fish and tanks were fantastic!