But whilst the ombudsman upheld the principle of the client's complaint, it found the compensation Cofunds had eventually offered her - now at a total of £275 - was sufficient.
In a case upheld in February a client complained she had been unable to log into the Cofunds platform from May 2018 and Aegon had not completed a transfer request which had been placed at the time.
When the client was eventually able to log back into her account she found her open positions had been closed and her funds were being held in cash.
The ombudsman heard how Aegon accepted the shares had been sold in error, offering to reinstate the client's positions and pay £500 in compensation.
When the client approached the Fos, claiming the offer of compensation did not reflect the "trouble and upset" caused by the problems, the ombudsman said he understood why the client felt the relationship between the two parties had broken down and the client had "lost trust" in the service offered by Aegon.
He also acknowledged Aegon had accepted the problems which affected the client's ability to log into her account.
Whilst acknowledging the situation had been "incredibly frustrating" for the client, the ombudsman found the £500 compensation offered by Aegon was "fair and reasonable" and decided it need not take any further action on the matter.
In all four complaints brought so far the ombudsman largely agreed with the level of compensation Cofunds had offered to clients.
The ombudsman clarified it was not its role to "punish businesses" and explained that instead it considers whether the action taken by businesses to rectify an issue was "fair and reasonable".