@liambolt private message me your mobile number and I'll check on it.
hey Sebasstian, my mobile number is <removed>. cheers
No issue with SMS from Spark to you. Can see last successful deliverys from Spark numbers to you on 15/07.
I suspect this is actually an iMessage issue not an SMS issue.
I am also having this issue and hoping that Sebastion the Ninja Extroardinaire will help me out.
Started with an iphone 6 but just upgraded to an 8 and it is still an issue.