It's time to learn how to do it yourself. It takes about 2 gallons of RV antifreeze at less than $3.00 a gallon to do most RV's. Even you get extra and have room for cushion, 4 gallons is still less than $12.
I wouldn't waste my time taking it back. I'd check it out myself.
Here's a somewhat easy way.
Although you are not hooked up to water and hopefully your fresh water tank is empty, turn on your on board water pump and let it run. It will probably be pushing air, but that's perfectly fine and it does not hurt them to run with no water. Mine have been on for hours at a time with no water before (long story), so running with no water a few minutes will not hurt anything.
After the pump in on, simply go to each faucet and turn on hot and cold. It should spit something! If it spits some pink, you are good. If it spits clear water, it's not been done right. Check each faucet, hot and cold one at a time. It only takes a second to turn the faucet on and off. You want the pump to keep pressure as much as it can so you can try the next faucet.
If nothing spits, I'd be coming back to these forums and asking the question, "how do I winterize" or simply watch a few Youtube.com videos.
Winterizing is so very easy, you really should do it yourself. There are 2 methods: 1) Pump the Pink or 2) Blow with compressed air. or 3) a combination of both.
I pump the pink, and then follow up with blowing the pink out. That puts more down the drain and into the holding tanks. Total time from start to finish and throw away the gallon jugs ... 10 minutes.
Good luck.