[Lara]

My 2cents worth from a customer relations perpective...

Consider laying it all out in a letter, with your reasoning and evidence and sending it to the company priciple: the highest manager you can access, or a comsumer care address if they have one.
Be polite, make no threats and don't get emotional (get someone you trust to read the letter before you send it) Lay out the facts, refer to people and times of conversation/contacts. Quantify your loss/out of pocket situation and ask for a refund on the unecessary work. Importantly ask for a reply in writing.
Keep a copy and a note of when you sent it. add the copy to the file with any other notes you may have taken.

Tedious and a bit old fashioned? Maybe, but this is the sort of stuff small claims, consumer protection who ever, like to see as solid evidence you have tried to address the problem. Also whatever the company replies back to you they can be held to.

However, they may simply argue they were only faultfinding a difficult, unusual or obtuse fault and their actions were reasonable, if a bit long winded and not very effective.

You must have chosen them for a good reason in the first place. If you do get to speak with a senior manager reinforce you chose them bacause of (whatever.. price, range, combination of products) but you have been terribly disappointed by the service and now regret the choice you made, however the true test of a company is what they do to fix a problem when the problem is brought to their attention and if you can get a good outcome you might consider them again..

I've dealt with companies who have had bad front line staff, done a crap job, but management have been very grateful that I have bothered to tell them how it was. Of course others haven't cared a jot and I've never gone near them again :-) but its fair to give the benefit of the doubt until proven otherwise..

Good Luck
Lara