|Eventually they sent me a router free of charge but it made no difference whatsoever|
I could have told you that would be the case. I've worked with many different makes/models of SOHO Router's and they're a relatively simple device. If one make/model works on your connection, every other make/model should to.
As I said in my last post. The issue was their problem all along, not yours.
One day perhaps these people will realise that routers and telephone extensions do not just change form fast speeds to slow speeds overnight withouit a reason.
Chances are the people you're talking to on the phone are simple helpdesk people with little or no experience in computing. They have a Q&A database and step-by-step guides to go through but if a problem isn't in their database, they can't help you.
Typically, with the better providers, if a situation is beyond the helpdesk's abilities, they (the helpdesk) escalate the issue up to the next level of support who are the people witha actual training, knowledge and experience. However, this didn't seem to happen in your case.
And changing routers to the main socket or the position of it is not probably the answer
Again, we must do things different in Canada. I've never heard of a "main socket" for phone lines in homes. There are two different things I've seen used in homes. A simple litte box with 4 screws. The incoming telephone is connected to two of them and all extensions in the house connect (according to color) to the same two posts. The other is a small punchdown box that achieves the exact same thing.....which is to say, break a single incoming line out to multiple extensions. These units don't actually do anything other than break a single line into multiples so they can't, and don't cause, slowdown issues with the network.
Whatever your ISP screwed up at their end, they found and finally fixed and that's why your internet bandwidth returned to what it should be.
Considering you're now having email problems and they host your email and control the server...........that means they've now messed up the email server too. Which they may or may not eventually fix. If it were me, I'd be looking at other providers and if there are any available in your area, I'd be signing up with someone else and dropping those losers as fast as I could. They (your present ISP) are apparently not very skilled at what they're doing and seem to be causing more trouble than they're worth.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.