Processing of online bill payments submitted by millions of households have been frozen for days on servers owned by Australia Post after a meltdown of computer systems.

The operating platforms of AusPost’s online payments gateways – SecurePay and Direct One – have been crashing for most of this week causing major headaches for companies that process transactions through both companies.

SecurePay is one of the largest internet payments services in the country and processes online payments made to billers such as Origin Energy, NRMA, BUPA and Estee Lauder.

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The collapse of both companies’ systems has meant that billers that use the service have not been receiving payments made by customers.

SecurePay’s Twitter account documents the havoc wrought by the malfunctioning technical systems this week.

The meltdown means that many customers who have already paid for online transactions are likely to begin receiving late payment notices from some billers.

It is not clear whether SecurePay will be reimbursing customers if billers levy late payment charges.

Here’s a sample of the company’s efforts to keep clients at peace despite continuing problems with the service since Sunday morning.

SecurePay is currently experiencing a service degradation and is in the process of recovering our services. Next update at 12:00pm.

— SecurePay (@SecurePayAus) April 27, 2015

Limited services are now available to customers. We are still in the process of recovering all services. Next update at 1:00pm

— SecurePay (@SecurePayAus) April 27, 2015

Due to yesterday’s outage we are experiencing some service degradation issues. We are working to remediate. Next update12:30pm

— SecurePay (@SecurePayAus) April 28, 2015

Dear Customers , Most services have resumed Restored today: 1) Camtech – payment processing 2) Direct One – direct interface

— SecurePay (@SecurePayAus) April 30, 2015

An Australia Post spokesperson said the extended outage had been caused by a security upgrade.

“SecurePay has experienced intermittent network outages due to important security upgrades,” the spokesperson said.

“These outages affected online payment services.”

The spokesperson said SecurePay systems for in-store payments, post office services and mail delivery had not been affected.

“We have continued to keep our customers up-to-date during this process, on a direct basis and via social media,” the spokesperson said.

“We are confident the majority of services have now been restored. We are working closely with the remaining impacted customers.”