Hi there, sorry I was offline by the time you had replied last night. I would agree that it appears employer is simply trying to use this as a reason to avoid paying you what you are due. Have just latched on to a strict interpretation of the restrictions you were working under and applied them without any reasonableness or degree of flexibility.
If they were to try and accuse you of breach of these restrictions, then really there has to be something of a common sense approach. For example if you had contacted clients with a view of affecting the company’s business, e.g. Trying to poach their business after you leave or affecting the way they do business with the employer, then it would be reasonable for the employer to try and accuse you of breaching these terms and take action. However, a phone call, especially one that you did not make but received and for a short duration, and from someone you knew personally should not be seen as a serious enough breach to justify dismissal on grounds of gross misconduct.
In the circumstances you are able to consider pursuing them for wrongful dismissal, which is a dismissal for breach of contract to try and get your notice pay.
This is your basic legal position. I have more detailed advice for you in terms of the steps you can follow to take the matter further, which I wish to discuss so please take a second to leave a positive rating for the service so far (by selecting 3, 4 or 5 stars) and I can continue with that and answer any further questions you may have. Don’t worry, there is no extra cost and leaving a rating will not close the question and we can continue this discussion. Thank you