Buderus GB012 Combi Boiler Chronic Heat Exchanger Failures

the house I'm renting installed a Buderus brand GB012 model combi boiler, all because of some condensing rule. At first, everything seemed hunky-dory, but as luck would have it, the real troubles kicked in right after the warranty said its goodbyes. I've had this boiler repaired not once, not twice, but a mind-boggling three times. I'm exhausted from dealing with these endless repairs. Just when I thought things couldn't get any worse, bam! The boiler decides to hit me with a heat exchanger failure. Apparently, this is a recurring issue with these models – the technical service has given me a not-so-sweet estimate of around 4000 for fixing the heat exchanger failure but my wallet's definitely not prepared for that kind of expense. And to top it all off, winter's creeping in, and I'm left wondering how I'll survive without the cozy warmth of natural gas. buying this Buderus boiler might just be my biggest regret. If you're in the same boat, you know exactly what I'm talking about. This heat exchanger failure situation is chronic, and I'm pleading for some understanding.