Dotsure Pet insurance

My two geriatric German Shepherd dogs were with Petsure until 1st October when Petsure was bought over by Dotsure. At their ages I do not have the choice to move to another company. Petsure was costing me R598/month for the two for R45 000 annual cover. Dotsure is now costing me R823.34/month for R29800 cover. So I am getting 51%LESS cover for 37.7% more cost. In addition, Medicines annual limit with Petsure were R3800/dog per annum, whereas with Dotsure it is R2380/dog per annum ie 62% less. Surely if a company buys another company those clients should be afforded the same cover until their demise or until the client cancels the policy? The dogs are extremely healthy for their ages at almost 11 and the other 10 1/2 years old, but now need geriatric medication. I was upfront with Dotsure with regards their existing conditions and chronic medication, which they even listed in the Policy wording I was given. For example, I stated that both were on GCS Dog which is a Joint Supplement for Spondylosis which Petsure used to cover. Now they tell me that they do not cover "Nutritional" Supplements which is in their policy wording. As I said to them, GCS Dog is a JOINT supplement NOT a Nutritional supplement. A nutritional supplement is a vitamin, a mineral, a protein or a probiotic. A joint supplement is a treatment for a medical condition and it is a fact that it relieves pain and reduces inflamation. I really do not think that I have been given a fair deal. They are not comparing apples to apples, but apples to vrot bananas. Another pet insurance company, Medipet, offers similar cover to what I had at less price to Dotusure, but no company will take on my dogs at their age. Is there any advice as to what I can do?