Dean Finnigan, a keen investor and client of Oxfordshire-based CMS Financial Management, transferred his final salary pension into a self-invested personal pension on the Aviva Wrap in October 2017.
The investor said he was sold the platform on the basis that he could control some of his funds to be able to do some direct trading through his adviser.
But following the switch-over of the platform to FNZ technology in January problems started to emerge.
The platform would not allow Mr Finnigan to trade direct equities, while some trades were duplicated, and others not carried out at all.
In particular, the issues centred on the buying and selling of exchange traded funds, which are risky because they are subject to unit price fluctuation.
Several complaints to Aviva proved fruitless, although the provider did assure the investor it would make up for any losses caused.
The problems ultimately caused friction between him and his adviser, however, who had sold him the platform in good faith.
Mr Finnigan told FTAdviser: "I am trying not to get frustrated with my adviser as I know ultimately the issues are with Aviva.
"But I paid them (a lot of money) for advice and they put me on this platform.
"The fact they are nice guys doesn't help the frustration I have had or the fact I am paying expensive monthly charges ongoing for something that isn't working for me."
He said: "None of the figures ever make sense. I can't get an accurate view of what my portfolio is."
Had it not been for a promise to be able to do flexible trading, he said he would have moved more money to another Sipp he held with Barclays.
David Carter, director at CMS Financial Management, said: "Whilst we have a good relationship with Dean, the issues initiated by Aviva invariably causes understandable frustration for both himself and us.
"We have been very disappointed with Aviva's platform migration, the communication from Aviva to ourselves and clients and the general lack of information/timescales provided."
He said Aviva's lack of communication meant he was often left in the dark to handle client frustrations without support from the provider.
However, he added: "I appreciate we are here to bridge the gap between the client and provider so understand this will happen in these circumstances."
Mr Finnigan’s case is the latest in a string of complaints about glitches with the new platform.
The platform was unavailable for six days beginning on the evening of 17 January and just one day after it came back online advisers and their clients found themselves locked out.
Since then there have been a litany of problems with processing adviser charges, switching funds, processing income drawdown, facilitating Isa contributions and erroneous alerts sent out indicating huge value drops in client portfolios.
An Aviva spokesperson said: "Firstly, we would like to apologise to Mr Finnigan for the inconvenience he has experienced following our platform migration, and for the delay in dealing with his complaint.
"We have been in touch with Mr Finnigan to work through the specific details of his complaint, and will be taking a number of actions to ensure his instructions are carried out and that he does not suffer any financial disadvantage through delays in trades.
"Following feedback, we have amended the way the platform sells from models, and the way valuations are shown online has been updated.
"We appreciate that customers and advisers have encountered significant problems since the replatforming took place, and we are dedicating additional resource to dealing with complaints and working towards ensuring any redress is settled quickly and appropriately."
carmen.reichman@ft.com
