Thank you for your question. I look forward to working with you to provide you the information you are seeking for educational purposes only.
Under the law, when a tenant on a storage unit is late on rent, the storage company has a right as long as it is in the contract to seize the unit and contents for auction. They cannot seize the contents until the time that the contract states for late payments, since they can refuse to take payment beyond that date in the contract. So your first step is read your contract with the storage company.
WA RCW 19.150.030 states, When any part of the rent or other charges due from an occupant remains unpaid for six consecutive days, and the rental agreement so provides, an owner may deny the occupant access to the storage space at a self-service storage facility.
Additionally, RCW 19.150.040 states they had to give you notice and says:
When any part of the rent or other charges due from an occupant remains unpaid for fourteen consecutive days, an owner may terminate the right of the occupant to the use of the storage space at a self-service storage facility by sending a preliminary lien notice to the occupant's last known address, and to the alternative address specified in RCW 19.150.120(2), by first-class mail, postage prepaid, containing all of the following:
(1) An itemized statement of the owner's claim showing the sums due at the time of the notice and the date when the sums become due.
(2) A statement that the occupant's right to use the storage space will terminate on a specified date (not less than fourteen days after the mailing of the notice) unless all sums due and to become due by that date are paid by the occupant prior to the specified date.
(3) A notice that the occupant may be denied or continue to be denied, as the case may be, access to the storage space after the termination date if the sums are not paid, and that an owner's lien, as provided for in RCW 19.150.020 may be imposed thereafter.
(4) The name, street address, and telephone number of the owner, or his or her designated agent, whom the occupant may contact to respond to the notice.
So, they have to give you the notice and they are in violation. At this point, you have the right to sue them for breach of contract and violation of the WA law regarding seizure of your unit. When you file suit, you would also file a motion for a temporary restraining order preventing them from selling your unit at auction. The court would award you the right to your property in exchange for you paying back due rent.
This is your only option remaining now that they are not allowing you access and have not provided you any of the notice required by WA law.