Telephone woes

I bought a new set of phones last week as there had been terrible crackling & noise during calls, I managed to get them fully charged over the weekend (after returning the first set purchased as they weren't taking a charge)......
Only to discover that it was the line not the old phone.....

Engineers duely arrived today - diagnosed corroded cable & rectified - or so we thought.....but within an hour the noise is back as bad as ever....

But on the plus side they did also upgrade my modem from 'obsolete' whilst they were here so fully wire free now:-)

Now just have to wait till Thursday for engineers to return for the landline