Customers of Royal Mail's online postage services have suffered yet more intermittent outages today and over the weekend.

This is the fifth consecutive month that users have experienced problems trying to access the Royal Mail's SmartStamp and online postage service on the Capgemini-managed website since online data was migrated to new servers in December 2011.

Royal Mail first acknowledged the problems in its Twitter feed this morning at 11:01 GMT: "@mgdm We're aware there have been some issues with the site over the weekend & this morning Michael, so sorry for that."

Later in the day, at 14:07 GMT, Royal Mail updated its Twitter feed with an apology.

"SmartStamp & Online Postage customers - really sorry for further access issues. We're investigating these now."

The fact that the website glitches have been recurring since December have not bypassed customers.

One, a small business posting on Twitter under the name Sharon @littlecottonsoc, said: "@RoyalMail your site has not been right since your changeover before Christmas! Why is it taking so long to get everything sorted?"

Meanwhile, as customers rush to buy stamps before the price hike due at the end of the month, one customer said that the online problems have only added to the pain.

@rebeccaejulian posted on Twitter: "So I can't buy stamps from Viking or Superdrug and now the @RoyalMail is down! Well isn't that just brilliant? #losingfaith"

Royal Mail has yet to respond to requests for comment at the time of writing.