Swansea-based Keith Lewis said he was given just weeks to respond to historic complaints while recovering from a major operation where a kidney and part of his colon were removed.
He had sold his business to a Cardiff-based company in 2011 after becoming ill and was hospitalised earlier this year.
Mr Lewis said: “The Fos has been pursuing me and I told them I couldn’t respond because I was in hospital.
“They were giving me weeks to respond but I needed months. I am still very weak physically.
“In two out of the three cases brought by Fos during my recovery, which I felt able to look over, resulted in them changing or decreasing the amounts in its final decision.
“But once they have made a decision there is no going back, even though they have made a wrong decision.”
Over the past year, according to its website, Fos has made final decisions on three complaints relating to Mr Lewis’s former firm.
The first related to an investment in a bond and a loan which the ombudsman upheld and ordered compensation to be paid.
The second, in which the adjudicator acknowledges Mr Lewis has not responded to on more than one occasion, relates to a transfer from a group personal pension plan to an unsecured pension and was upheld.
The third, also upheld, relates to advice to take the tax-free cash sum from a client’s pension funds and to then invest it in an investment bond.
Once an ombudsman has reached a decision, it cannot be challenged except through the courts.
Independent assessors can be asked to look into cases, but they are tasked with examining solely how the case was handled by Fos rather than looking into the substance of the complaint.
Mr Lewis said he has contacted the Fos assessors but said he was not satisfied with the response.
He said: “There is no process in place for an IFA to appeal which is outside Fos and the whole process in biased against the IFA community.
“It needs to be far more open.”
This is not the first time a regulatory body has been accused of looming over an adviser’s hospital bed.
In 2012 the Upper Tribunal ruled against Middlesex-based adviser Athanass Stefanopoulos over his failure to pay his regulatory fees to the former City regulator, the FSA, despite the adviser having a heart attack and being in hospital for eight weeks.
Right to reply
Lena Nunkoo, a spokeswoman for Fos, said: “Typically we do set time frames for both the consumer and the business involved to respond – as you can appreciate without this, cases could be left open indefinitely which would be impractical.
“That being said, we are always open to extending the time a consumer or a business has to respond if there are extenuating circumstances – such as an illness.
“Looking at a couple of cases that were involved in I can see that they were on-going and left open for over a year – with several letters sent to the business requesting information.
“If the business or consumer had any information that it wanted us to consider we would have expected it to be sent to us during this time.”
