CLA220 (2013) Bluetooth update

[Jhonny]

Hi all,
I am new in this forum.
My CLA 220 (2013) audio system (bluetooth) does not work good enough (bad sound quality -both senses-). Do you have any idea on how improve this audio feature -mainly phone calls-?

Need for software update? (how to do that??)
Need to change hardware?

Any advice from your side would be much appreciated!

Kind regards,
Jhonny