Please help... losing my mind AND my money!

I bought a home that had a Coast spa built into the back deck. I didn't know anything about it so I had a repair guy come out to look at it. We got it running (everything was working), but before we could add chemicals and enjoy it, I noticed a leak coming from under the skirt. Since it was built into the deck, I had to get 12 of my buddies to lift it out. The repair man came back and found a crack in one of the manifolds. He repaired and we put the tub back in the hole. When we went to fire it up, the factory control board was all out of whack... the jet button turned on the light, the heat up button turned on the jet, it was bad. So, the repair man suggested I get a new pack with top panel becuase it would come with a 2 year warrantee. So, he came out and replaced that. Got it ready to fire up again and when the pump 1 came on, it blew the lit off the filter housing. The repair man tried to put it on again, but by this time the threads on teh canister were disintegrating. So, he said we need to replace the filter canister. While digging the foam out around the canister, one of the jet housings cracked. So far, I'm into this thing $1700 and I haven't even gotten my swim shorts on yet. If I had known, I wouldn't have paid someone $300 to just haul it away. My question is... What would make the filter lid blow off like that? It worked fine a few weeks ago before the leak was fixed and the new pack was installed. Could it be that there was too much air pressure built up in the canister? Could it have been damaged previously and just decided to break all together? What are the chances that something else is really wrong that caused the filter lid to blow off and by replacing it I'm just wasting $300 more? I don't want this man to come out and repair it, only to turn it on and blow something else out. I cant afford to keep dumping money into something I can't even enjoy. Please help!!!