As a former orange broadband customer who suffered everything you are I felt I had to reply to your post.
I was a happy wanadoo customer when they got taken over by orange and did not have any problems until I moved 1.5 kilometers further away from the exchange. This is when I immediately started to experience the problems you are experiencing.
The experience of calling customer services was always the same. Talk through the problem, try some diagnostic tests and then have a line check done, ring back in 24 hours to be told the problem is down to BT, ring back in 36 hours to be told the line test was inconclusive and another one would have to be done. (a total of 16 line tests supposedly carried out, all inconclusive)
This lasted for a total of 5 months when I finally decided to change ISP and changed to SKY where for the past 6 months I have had a totally problem free service.
Orange did refund all payments I had made from the day I first started having problems, after I asked for compensation. Although this was not compensation as such, I was happy to be refunded without any hassle.
The only advice I can give is for you to change provider as quickly as possible.