Section 20. A provision in a retail instalment contract (1) for confession of judgment, power of attorney therefor, or wage assignment; (2) for the subsequent inclusion of title to or a lien upon any goods, other than the motor vehicle which is the subject matter of the retail instalment sale or accessories therefor or special or auxiliary equipment used in connection therewith, or in substitution, in whole or in part, for any such accessory or special or auxiliary equipment, as security for payment of the deferred payment price; (3) whereby, in the absence of the buyer's default, the holder may accelerate the maturity of any part or all of the total of payments; (4) whereby a seller or holder of the contract, or other person acting on his behalf, is authorized to enter the buyer's premises unlawfully, or to commit any breach of the peace in the repossession of a motor vehicle; (5) whereby the buyer waives any right of action against the seller or holder of the contract, or other person acting on his behalf, for any illegal act committed in the collection of payments under the contract or in the repossession of the motor vehicle; (6) whereby the buyer executes a power of attorney appointing the seller or holder of the contract, or other person acting on his behalf, as the buyer's agent in the collection of payments under the contract or in the repossession of the motor vehicle; or (7) whereby the seller is relieved from liability for any legal remedies which the buyer may have had against the seller under the contract, or any separate instrument executed in connection therewith, shall not be enforceable.