The FTC doesn't make the rules, it enforces them. Debt collection is set in stone via the FDCPA. There is nothing in it that states they cannot call Saturdays and Sundays or any other day for that matter, only that the calls must be between 8 am and 9 pm your time. It also doesn't set a minimum or maximum number of calls per day. It is up to a judge to decide when the number of calls becomes harassment and that is only after you have filed an FDCPA lawsuit. Now, for more on this subject:
Federal law (FDCPA) requires them to send you a letter (US MAIL ONLY) within 5 days of their first contact that contains their name, physical address, the creditor’s name, and the amount of the alleged debt. It also must contains “mini-Miranda” telling you that it is an attempt to collect a debt and that all information will be used for those purposes. The one other important thing that this letter must also have in it is that you have a right to dispute the debt within 30 days receipt of the letter and if you do so, all collection activity must be stopped until the debt is verified.
Read up on your rights here, get template letters to send and also make a complaint at this government site: http://www.consumerfinance.gov/
Also file a complaint with your State Attorney General's office.
List of State AG’s offices: http://consumerfraudreporting.org/stateattorneygenerallist.php