You need to invest in Greg Voros' Guitar Maintenance DVD. You can change your own strings. If you go up or down more than a string size you need to adjust the neck. Greg does a setup for every string change. I don't know why you would want to put on heavier strings. I think you should stick with the string gauge the guitar was designed for. I have seen comments from people like BB King and Billie Gibbons which basically say "why work harder?". I have maintained my Gibson Les Paul Studio and 3 other guitars for 9 years now. I have done a few minor truss rod adjustments, many string changes, and setups. String change is also a great time for a full cleanup. Taking all the strings off at once is not a problem, but not doing a complete setup when moving to heavier strings is bad. You can do better yourself with a little knowledge. I have never done a fret job. Maybe your guitar needed it, but maybe your technician is incompetent and greedy. Interestingly fret buzz is often caused by the neck being too straight, but I would think with heavier strings it would have been too bowed. The Les Paul has many adjustments that can be made, and once dialed in it rocks. It seems complicated until you see the Greg Voros video.
Check out Taylor's website for the "Taylor Method" of string change because it is pretty simple and works for electric and acoustic guitars.