Glad your line seems more stable with the ECI modem, did he do anything else other than swap the modem out?
Lots of line checks with his JDSU which all passed with large margins, a line test with a large blue phone shaped device with a keypad which passed with flying colours, and also installed a new faceplate on the BT socket. He said there was nothing wrong with the old one, but thought he may as well do it while he was there.
He could basically find no issues so swapped the modem as I was initially supposed to have had and ECI model fitted but the contractor who did the install fitted a Huawei as it was all he had on his van. He then explained he couldn't reset my profile while onsite because he had found no fault, and I should contact my ISP to get that done.
The ISP contacted BTW/OR the next day and my profile was reset.
Now my fingers are firmly crossed that DLM leaves me alone.