Check out won't workor

I tried for over 2 hours last night to order an AC.  Finally got the itme to my shopping cart, hit checkout and nothing.  Buffered forever. Tried many times, same thing.  Also, screen kept taking me back to sign in.  When I put in my user ID, said didn't recognize, but icon said welcome using my name.  This is a nightmare  and was happening over three months ago when I tried then to order something online.  I went to customer service, they ordered it for me and told me they were having problems with their online service.