Currently, I have 6GB data for$65 before Tax.
I just checked my account and saw that my plan will now have 1GB only.
I did not sign up for this, is this true? If I click 'View full plan details' my add-on is gone and now I can only get 1GB data, not 6GB.
What the heck is happening?
Since you said that the add-on is gone it sounds like the extra 5gb was a promotion that lasted for a specific time and has now ended.
If you check your last invoice or possibly the last 3 invoice it would have stated the promotion is coming to an end.
Since this is account related it would be best to contact customer support and they have go over your account to provide clarity.