Amazing! I have the exact same OTTAWA tub and have experienced very similar problems!
First of all, thanks for posting the manufacturer's phone number on the web. I've looked everywhere and YOUR review is the only place it can be found.
Don't believe me? Do an online search on "Great Lakes Hot tubs" and try to find the manufacturer's phone number. You get alot of sales numbers, but no manufacturer contact information. What does that say about these tubs?
Here's my situation:
I called my "sales" rep - this guy is the epitome of a weasel - to find out why my hot tub never shut off. He charged me $75 for the visit and $25 to tell me it was either the controller or the mother board (I already knew that) and should go ahead and have both replaced!
His diagnosis was based on hearing me describe the symptoms instead of actually debugging the hot tub. So, for a measely $1100 they could replace both parts and the problem would be solved. Let me repeat that: $1100 for a product under warranty.
The sales weasel even brought his 14 year old kid out to verify the problem. I can't begin to describe how much that made me feel better. I told them to get off my property.
I still needed to fix the tub. With a simple fluke multi-meter and about 5 minutes of my time, I found a control button stuck on the controller - a simple touch pad button jammed in the "on position". I opened up the controller and repositioned the touch pad. It works fine now.
If you buy one of these tubs you are either going to get ripped off financially, (with or without a warranty), or you will have to fix it yourself.