They had my amplifier for FOURTEEN months and still did not fix it.
I had to contact the manufacturer of the amp myself.
I sent Robert (the owner of SerTech Electronics) emails on what to do and to contact the manufacturer. After several weeks I contacted him again and he said he doesn't read emails.
He originally said he sent emails to the manufacturer, and hadn't heard back, but the manufacturer said they never heard from him. Come to find out that he had been using the wrong email address.
The absolute worst retailer / business I have ever dealt with in my entire life.
The owner, Robert, just doesn't care.
Strongly NOT RECOMMENDED.