A. Your command of English, is better than many native born "Americans" - no apoligy needed, IMO.
B. I won't comment on the car as, well, I have a 1970, a 1980, and 1982 car and drive a well-used 1995 pickup........
C. we are all under GREAT STRESS lately, in the world, our own regions, and our jobs. I"m sure even the French are realizing this in their economy and jobs. For us here, we are SO stressed, it's showing up in the form of illnesses, poor vision, depression, anger/short tempers, and loss of productivity. Management doesn't realize that more pressure actually results in less output, so it's counter-productive to demand more than one can possible put out - and do a GOOD job, because it causes LESS, not MORE, to be put out. Here, we are also faced with huge budget cutbacks, loss of jobs (and the union vote looks BAD here) stress and anger we understand............ you are not alone - and believe it or not, are among friends.
That being said................ hang in there. If it can't be solved in the forums, then open a ticket - and be relentless! Don't let the ticket be "closed" until you have a solution, or find a solution isn't possible in your case. Hard to imagine, but I've seen it in the past - you have to work "band-aids".......... and other products aren't always the answer. Each has their own set of issues.
Not that a technician is necessarily "bad", but each has different experiences and methods - so if you get to a stopping point, get hung up with one, ask for another, or ask for an escalation (sorry about MY spelling and English!!!!) some are simply better at certain things than others. Who you get may or may not be the best person for your particular issue or situation. LOL - when we call Cisco, we routinely go through 2, 3 or even 4 techs before we get solutions!
Gather all the data you can, list it - in sort of an outline or bullet point list. There are troubleshooting things you can do - network "sniff" traces, etc.
The more information you can supply - exact OS version and patch level, service packs, servers - virtual or physical? Machines in each location, number of locations, number of subnets - are they all on one network, or multiple nets/subnets, any clue can help, no matter how small it may seem.
Yeah, I know some of it takes time - I've been months on one of our problems here, and weeks on another, and this week, more testing has actually brought up more QUESTIONS, and not a single answer!