Whirlpool Hot Water Heater / brand new/doesn't work

I bought my Whirlpool 30 gallon gas water heater at Lowe's in November, 2007. It worked a little over a year and has had the same problem: the flame will not stay lit. My husband I has already spent several hours trying to repair it, at Christmas with family company.
They told me at Lowe's that I needed a complete repair kit, that that had fixed all the ones that needed repaired. It did not work. The next one I buy will not be a Whirlpool nor will it be at Lowe's. If there is a problem with a certain hot water heater then why do they continue to sell it? I was told that at one point Whirlpool pulled the left threading thermocouples from the stores and people had to wait several extra days to get the replacement from the company.
My husband thinks he now knows what is wrong and will try to repair it.

you can't buy thermocouplers when they go bad. had to have a new conversion kit sent to us because they knew it was bad. now we have to have another piece sent to us. so every time we need hot water we have to go light it and wait for the hot water to heat then turn it off so the gas doesn't leak. we will NEVER buy a whirlpool heater again.