Started overheating first of July

Help! My 2001 Silverado extend cab started overheating first of July. I took it in and they flushed the radiator and said it would be fine. It continued to overheat, so I took it to another place and they said there was a hole in the heater core and the water pump was bad. Well, I had just replaced the heater core 15 months ago and paid close to $1000. I took it back to the first place and told them that the heater core was bad and I was not paying them again. Well, after going back and forth they replaced the heater core and I only paid for 1/2 the labor, so it was $300 dollars instead of $950. It still ran hot. I took it back, they replaced the water pump. It still ran hot, I took it back. They replaced the thermostat and the radiator cap. It still ran 260 degrees after about 10 minutes of driving. They then said that it was either a blown head gasket, or a cracked head. (BTW this was at a national chain place, not just a mom and pop place.) They said it would be 1500-2500 dollars depending on what and how bad. I said no thanks. Someone recommend on of the stop leaks products so I researched it and gave it a try. It seem to work but after driving about 30-40 minutes the temp went to 235. I took it to a shop and they told me there was no sign of head or gasket damage, no leaks at all, but that the liquid glass I had used had clogged the radiator and I would have to have a new radiator. I called a radiator specialist and he said he could "rod" it out and we would not need a new radiator. I took it to him. He called back, the radiator was fine. No clogging, but there was a leak in one hose and another hose was loose. He fixed it, pressure checked it no leaks, all is good. I just picked it up. Drove it. After about 25 or 30 miles the temp slowly rose from 210 which I was told was normal to 235. It stayed there and did not go higher. Help! What is going on? What could it be? Is it because I am a woman that I am getting the run around, or am I just dealing with idiots? Any advice or suggestions would be greatly appreciated!