You may want to review the Commentary to 226.5b:
Paragraph 5b(f)(3)(iv)
1. Beneficial changes. After a plan is opened, a creditor may make changes that unequivocally benefit the consumer. Under this provision, a creditor may offer more options to consumers, as long as existing options remain. For example, a creditor may offer the consumer the option of making lower monthly payments or could increase the credit limit. Similarly, a creditor wishing to extend the length of the plan on the same terms may do so. Creditors are permitted to temporarily reduce the rate or fees charged during the plan (though a change in terms notice may be required under §226.9(c) when the rate or fees are returned to their original level). Creditors also may offer an additional means of access to the line, even if fees are associated with using the device, provided the consumer retains the ability to use prior access devices on the original terms.
_________________________
The opinions expressed are mine and they are not to be taken as legal advice.