Does that necessarily seem like a bad idea to you?
I think it's unlikely this matter will be settled during the lifetime of any present ThaiVisa Forum member.
So you're looking for a computer shop in the Udon Thani area.
How old is your Mac? is it out of the warranty period?
One option could be to mail it to one of the Apple stores in Bangkok.
In the past there were movements urging a "none of the above" option on the ballot. I can't think of a more appropriate situation for having that choice available,
We'll have to mark you down as being opposed to agent use.
The cost of using an agent isn't a detriment to me and even though I'm retired, I love avoiding standing in lines.
To each his own, however.