After 6 years my renewal is up to £172.79 per month from £44.88 a huge hike in one go.
Reason I had too many claims apparently last year and they draw my attention to Section 12 General conditions and claims.
12.1.13 When inviting renewal of this policy we may, at our sole discretion, and for any reason we deem appropriate, taking into consideration, (but not limited too) your pets age, medical and/or claims history, change cover, benefits, premium, terms and/or conditions.

At age 8 I will have to pay as well as excess 35% of total too,
reason for this allows them to provide cover for the older pet whilst maintaining a cost effective policy as they enter old age.
Yes you do expect increases but not so you are priced out and will go away when you cost too much, or if you stay have such high premiums you will paying for your pets vet bills yourself.
Don't worry though, you will be fine as long as your pet isn't ill, has an accident or anything else that will need a claim. I took out their best policy with the highest rate of cover believing I had peace of mind.