Shopping favorable produckt bad

I have long been waiting for the rate, because I still hoped a solution with the seller to find.
My laptop had been at the beginning of recurring problems, system crashes, Internet was slower than my 10 year old PC.
I have therefore contacted the seller who answered promptly (Unfortunately, no telephone service). So I had the computer I need to work to return.
There the hard drive has been replaced and in no time I had the PC again.
But it all started over again ... and now I had to send it back again, but that does not work because I need the PC for my work. So I have to buy a new one ... at my expense .....