Collectors think of the people that owe money as scum. I know that because I used to work in collections where the general attitude was that these people were purposely trying to avoid paying their debt. There was no thought to what their circumstances were. Collectors break the law on a daily basis, it is normal and expected. If a lawsuit is filed against a collector, that collection rep is thrown under the bus, as the firm denies that it is standard operating procedure. If everyone knew their rights and complained, the system would be overwhelmed. An increase in complaints simply means that more educated people are dealing with collectors, and know how to fight back. We need more people to file complaints in small claims court on a regular basis. Debt counselors should be educating and training debtors to stand up for their rights and enforce them. Otherwise the law means little.

Being in the collection industry I can shed some light on the information you have provided.

Increase in 3rd party complaints and reduction regarding in-house complaints. This has been created due to the current practice of selling debts. The creditors are being so overwhelmed with the increase in past due accounts that they are unable to staff the appropriate personnel to work the enormous number of accounts in-house or by outsourcing. To offset these losses thay are instead selling their debts to collection agencies who in turn are staffing up to handle the increased volume. The collection agencies are increasing their staff sometimes with unqualified personnel who do not have the proper training.
Complaints regarding larger balance than owed. This is normally caused due to accounts that are accumulating interest. In most cases when a collection agency adds interest on a purchase account the information they receive is minimal on interest accrued and the time frame involved. Meaning they don't know what interest has been added through which date. Most agencies will not add interest due to this discrepancy but others do their best to calculate the current interest but fail miserably due to no set pattern across all accounts.
Accounts not owed. This can be caused for several reasons. Accounts not owed due to Bankruptcy, already settled, Unknown creditor, Fraud and Identity theft. The cause in most cases is purely clerical. If a creditor fails to receive or fails to document and properly close an account that met any of the above criteria the account will find it's way to a collection agency who purchased the debt. The sad part is that without a system of policing the industry in place to prevent the selling of these accounts this will continue to happen. In most cases the collection agency has a grace period to find out if the account is not collectable for any of those reasons and can charge the seller back. The truth is that this debt only ends up being sold from one entity to another.
Unknown creditor. These are normally telecom or cable accounts due to the companies buying and selling each other. One company buys out another and absorbs their past due receivables. The accounts are not labeled correctly when they are sold to include the original company where the credit was given. The last thing a collection agency wants is to call someone that doesn't owe a valid debt.