Repair costs and frequency frustration

We like our 15 year old 30 ft. Class C we've had for 7 years. Reliability has always been up and down. We had a pretty good couple of years of repair costs we could live with but now we're discouraged and don't know what to do. Many costs this past year; some routine and expected, some not. Must have totaled 7 to $8000 and today, after $300 dollars of work, I'm told that I need a differential bearing which this shop can't do which will cost thousands; not hundreds. Only has 67000 miles. We're reluctantly considering downsizing to an older used Class B, like a Roadtrek but seems like we would have to repair our present one to sell it. I'm not asking for an answer; just venting. Oh, spending over $30000 for a replacement is out of the question. Thanks for "listening"