SMS messages being converted to MMS messages

[burgermaster]

I recently sent an identical message to 14 people.  I had to send it twice to 7 people at a time.  The first 7 messages were not charged but the second lot were converted to MMS and I was charged 35p for each of them.  I checked out the Q&A and it said "Sometimes a text is converted to a MMS by the phone's operating system.  This is beyond our control. It may happen when you send a text to several people at once".  So how come the first 7 were included in my allowance but the second lot was converted?  I don't hold with this "it is beyond our control" malarky - it's not consistent.  I have been told I will be credited, but it shouldn't have happened in the first place!  I am using an iPhone 7plus

[BandOfBrothers]

Hi @burgermaster

My opinion is that mms is old and should be dropped. 

I send long texts or pictures via email, Facebook Messenger etc. 

There is a feature I believe in the iPhone's settings that you can use to stop texts converting to mms.