Thank you for the question. First thing to do is play (only) the ground fees. In relation to the rest, you will need to ask them to prove they have sent this to you, if they are not able to show they have sent the notification (assuming a time wasn't set out in your original contract) they will not be able to enforce the additional fees. Unfortunately, the postal rule in law states they only need to prove they have sent it not that you received it so check your junk mail etc before fighting this.
I shall provide you with a helpful link that will assist you in finding a solicitor/representative near your local area. This will provide you with someone nearby your area who can assist you if required.
I hope this information proved helpful. You will find a local solicitor who deals with these matters on the law society webpage which is as follows;
https://www.lawsoc-ni.org/solicitors (N. Ireland)
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