Charging for group texting

[Puddings_pies]

I have a Samsung S7 on Android 7.0 with vodafone in the UK.

Using Disa.im I seem to be getting charged for group texts (sms) as long messages (mms)

There is an option in DISA.im to disable this. So the suggestion is that Vodafone are converting them to MMS.

Is this true? 

[hrym]

The support page suggests that this may be the case, although whether it's Vodafone or the message app you're using isn't so clear.   See the "Picture Messages" paragraph.