They refused to pay for my service stating that it is less than 12 months since the last one

They refused to pay for my service stating that it is less than 12 months since the last one. My policy states that which ever comes first between months and km’s. Now I was forced to upgrade to a higher premium because my car was already due and in for a service. Now I am on every 7 months with twice the premium. When I asked what happens if next service is only reached in 12 months, will they re- emburse? Nope, they will downgrade me. Total nonsense. They will leave you stranded.