Septic fields, am I being ripped off?

Carmen and I just bought our first house. The two major things it needs are a roof (that's fine, I roofed for a couple years), and a new septic field to be installed in a different location than the current one, which is ready to fail at any time.
The only company in town who does inspections is Roto-Rooter, so naturally we had them come do it. He said all 3 drain lines had collapsed, and the only reason the field is still functional is because the soil is so good in the yard. It's the original system, the house was built in 1981, and the lines are the old concrete tiles. Since they did the inspection, I also had them give me a quote for a new field.
Now, I know nothing about septic fields, so I gave them the go ahead to start mapping it out. I should have gotten other quotes, however I didn't because I had to leave for work right away. I work 5 hours north of Fort McMurray, Alberta.
They said they would start October 28, and quoted me $20,495. I thought that sounded high, but again, I don't know squat about septic fields. They mentioned it would be a Type 2 system?
I'm away at work, but Carmen said they stopped by the other day without any notice, and unloaded a small excavator and started digging holes in the back yard. Then yesterday at 8 AM they were there again digging right outside the bedroom. They left all these holes in the yard, then moved behind the shop into a clear spot in the trees, and decided the field actually needed to go there.
There are 2 neighboring wells and a creek all within 30 meters of where the field will go (30 is minimum distance away unless signed off by an engineer), but they said the engineer signed off on it, which is an extra $1000.
Carmen asked exactly how much they thought it would be, and to do a walk through with her. They were rude to her and told her they would tell the homeowner the price, and that they would do the walk through with the homeowner. By that, they mean me. Well, she is the other homeowner, and mentioned that, but they ignored her. Well now they want to start the field on Tuesday, and mentioned that the price was going to be more than they quoted me, but they won't tell me what it will be. I don't get home from work until next Wednesday.

So, if you can work your way through all that, am I being screwed? Is that a high price?
Other people we've spoken to have said theirs cost $13,000, another cost $8000, etc. Nowhere near upwards of $21,000. That doesn't include electrical to run the pump, and re seeding the lawn they tore up.

I posted this in the Canadian Region because I'm not sure how the prices will vary between here and the US, but feel free to post your opinion.