I entered into an informal loan agreement, the specifics of which were detailed in an exchange of emails. This loan was later increased and essentially became an investment in a joint business venture. The partnership was later dissolved by mutual consent (again there is an email chain to confirm this). My former partner and I later fell out and despite me continuing to comply with the previously agreed repayment schedule my former business partner has issued in the county court demanding interest at an extortionate rate when the loan / investment had not interest agreed. I have submitted the AOS but indicated that i would dispute jurisdiction - is this the correct approach? Is there any advice on how to proceed?