I've just noticed a warning message in Zoho Campaigns advising me that my subscriber count exceeds my plan limit. I have never seen this before as I have always run this account on a pay-as-you-go basis. 

On closer examination I see that it has now become a CRM Plus trial account that limits me to 2000 contacts. I've not had any notification that my account was being switched and I seem to have lost the large number of email credits I had on my account.