Sky Router: Internet Speed Issues After Line Repair

My ISP is Sky who I use for phone calls and internet, the line to my my house was installed by BT several years ago. I live in a fairly rural area and have never had more than a 1.5mb connection.
Two months ago a neighbor who was repairing his guttering accidentally broke the main phone line coming from the pole directly to our house (the ladder he used was left unattended and it fell over catching on the wire). The line broke in the middle of the length that runs from the pole directly in front of our house to the connecting shackle on the house fascia board, on the first floor.
I connected the broken wire back together, I only have one line in, so all that needed to be soldered were the white and orange wires. The other colored wires I cut flush. The remaining three steel core wires i used as holding wires. Everything was heat shrink sealed, insulation taped up, heat shrink over the whole lot and then more insulation tape put over the whole join, allowing around three or four inches over run at each end of the join. Afterward I did a quiet line test (17070 option 2) and the line was good. My internet speed was as per usual, 1.5mb.
Last Wednesday I was checking my email and web pages kept timed out, i logged on to the router and checked the speed I was connected at. My speed was 560kbps / 56k. After several router resets the speed was still not any higher. I did a quiet line test again and there was a considerable amount of line noise.
As it had rained a few times since my repair to the wire I thought it best to check to see if any water had gotten in. Unfortunately, even with all the insulation water had indeed got in. There was a score mark on the cable and that was the obvious route of entry. Upon opening the repair back up I could see the copper wire inside the orange line had turned black. I had to cut back the damaged line about 10 inches total, to get shiny copper cable and remove the scoring on the outside of the cable. I re-joined the line as I had done before. A quiet line test was good, but my internet speed remains at 560kbps / 56k.
I bought a new ADSL filter, and have tested the router directly in the master test socket without my phone extension, no difference in internet speed at all, and like I said the quiet line test is perfect.
Before I bite the bullet and get BT to come and renew the cable (which I am going to get done, when my neighbor can afford it) is there anything that I could have overlooked, or is it possible that the water has damaged something i.e. the Sky router or other parts of the cable?