Manufacturer Repairs? What is a reasonable time?

I sent a solid state amp back to the manufacturer in the USA on March 16 for a minor repair - one channel input not working - despite 4 phone calls and 4 e-mails - he hasn't even started the repair. Doesn't respond to emails but does answer the phone and says he is busy and is alone. I Will not identify him yet, since I'm not sure what the "norm" is, since I have always been thoroughly spoiled by Bel Canto, Atmasphere, CJ, AR, acoustic Zen, Cambridge, EAR, who respond immediately and usually have my unit back in 2 weeks. So when do I start to play "ugly", realizing that the economy is bad and manufacturers may be struggling?
Unless the broken equipment is a vintage or rarity, and he needs time to locate necessary parts; I say two to three weeks should be a reasonable amount of time for any amp repair because it takes less than that to completely replace the interior of any amp. There is no excuse if he hasn't even started after 3 months. Busy isn't an acceptable reason, it only means poor management.
IMHO, that level of customer service is unacceptable. Personally, I would already have purchased this amps replacement. I'd also keep pressure on the manufacturer to repair it, but I would sell the amp immediately upon it's return to me. I would make sure that I never had to deal with this manufacturer again!
Six weeks, which is Sony's time frame. Hopefully, unless it is still under warranty, you have put a 'stop loss' amount on the repair cost. Otherwise you leave them an open ended repair order, which never works out to your advantage.