4600 trio, one handset sound issues

[Tango_1224]

Less than 14 months ago we purchased the BT4600 trio for my elderly grandmother.
It was not cheap.
It was fine to start with but a month or 2 ago she started having issues with it but didn't tell us.
One of the handsets does not ring. It has no tones when you press buttons and the ear speaker is very very quiet (I can barely hear it so my hard of hearing gran struggles as you can imagine)
Do not disturb is off, the ringtone is set to maximum and the key tones are set to on. The in call volume is also set to maximum.
When you change any settings the phone does beep to confirm that this has been done so it is able to make sound.
I'm not best pleased as her phone is her lifeline. Is there a fix to this or will she have to swap the faulty phone for one of the other ones in the trio that works for the time being? Can she do this and have the main handset from base one on base 2?
Thank you
Emma

[NeilO]

@Tango_1224 can you try removing the batteries for a few moments to see if that helps? If not there should be no problem in swapping the handsets about. 

I'd also recommend contacting the 4600 helpdesk for advice.

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If your product is out of warranty contact BT's recommended agent

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