BANNED Essendon star Dyson Heppell feels a massive sense of injustice towards his club and individuals involved in their supplements debacle.

Heppell remains adamant he and the other 33 current and former Essendon players found guilty of doping offences have done nothing wrong.

The midfielder said he received written documentation about what he was given, but would not go into specifics because the legal process is ongoing.

Heppell is among 17 current players - 12 at Essendon and five elsewhere - who are banned for the season after the CAS verdict earlier this year that upheld WADA's appeal.

The banned players have said little since that verdict and they are now making a last-ditch appeal to a Swiss court.

"Embarrassed and ashamed, no, but I do feel angry," Heppell told AFL360.

"I feel let down and probably an overwhelming sense of injustice towards the club, a number of people who were at the club at the time and the investigation."

Heppell was with other affected players when they learned of the CAS verdict.

"It was utter disbelief, I reckon - complete shock," he said.

"I really didn't know how to react and it did take quite a while to process.

"The advice we were given right the way along is we'd done nothing wrong - and we knew that."

Heppell insists he would never intentionally take a banned substance.

"I have been called a drug cheat and at the start it did worry me, it was hard to swallow," he said.

"But I feel a lot of those people aren't really educated on the situation.

"It is a tough one, but now I don't get fazed by it too much.

"I know what we did, I know who I am, I know my morals and that goes against everything I believe in."

Asked if he had taken the banned substance thymosin beta-4, Heppell replied: "All I know is we were following a program that was run by the footy club.

"We were told everything was checked, approved and legal, and we were given written documentation supporting exactly that."

And Heppell is furious at the CAS assertion that the banned players did not declare all the substances they were taking on their anti-doping forms during the 2012 season.

"I actually find that quite ridiculous - we had absolutely no reason whatsoever not to fully disclose absolutely anything," he said.

"We've been completely open and honest from day one and we continue to be.

"I'm comfortable I know what I was given.

"We were told and provided with that documentation, stating that it was 100 per cent above board and completely compliant."

Asked how he felt about James Hird's role in the saga, Heppell said the former Essendon coach had been a real friend and mentor.

"It's more of a sense (that) I just feel let down by the footy club and a number of people at the footy club at the time," Heppell added.

"It's hard to label specifics on certain people at this time."

Heppell said he had no issue with the anti-doping system, but feels more let down by Essendon.

He admits he will struggle to watch Essendon start the season on Saturday night and has good and bad days.

"No doubt, you do go through a bit of a rollercoaster of emotions, but I'm in a good place at the moment," he said.