why do you think you will need electrician? is the socket multi purpose - phone and aerial for tv and power socket?
post pic of socket would help if problem on your side of test socket then more than like get charged callout £85
if it is just for your phone and broadband then no electrician is need
try connecting to test socket as any wires connected to the front plate are customers responsibility anyway and see if that works ok
you can add your photo using photos here
That reminds me of an old phone/analogue modem splitter, not a microfilter, are you sure that plug in unit is suitable for broadband?
I'm frightened I might accidentally dislodge something as it's all a tangled mass of wires!!
There should only have been two wires connected, unless of course you have other sockets elsewhere. They could easly cause disconnections.
I would be inclined to unplug that splitter, and use a microfilter if you have one.
wow long time since I seen one of these splitters