Hi @Rbradbury73, thanks for your post although I'm sorry to hear of your concerns raised here regarding your Oomph SIM.
It could be potentially, that as the SIM is subject to the Fair Use Policy, that it may have breached this.
The fair use policy is as follows:
"3.5. Usage of Unlimited Data is subject to our Fair Usage Policy. To help us identify whether you are using your Unlimited Data in accordance with the Fair Usage Policy and these Terms , we may monitor the amount of data you are using. Where you regularly tether to 12 or more devices, have used 650GB of data twice within a 6 month period, or have connected to a device other than an eligible device as stipulated in clause 3.3 of these Terms, then we may investigate your usage further to ascertain whether your Unlimited Data usage is for the permitted use. Where following such investigation we determine or reasonably suspect that your usage is for purposes other than the permitted use then we reserve the right to transfer you to a more suitable plan."
I hope this helps but it may be the reason why, does this explain things for you?
Many thanks
Tom_W