With turnaround times taking as long as 10 working days or three weeks, advisers say banks may be giving direct customers preferential treatment.
Geoff Bawden, founder of Q Group, said he had heard growing anecdotal evidence "which suggests that applications lodged direct with the bank are getting precedence over advisers' applications".
"It's not a good look if that is what is happening," Bawden added.
Another frustrated adviser got in touch with TMM Online to claim that direct clients were being given shorter turnaround times.
They said: "Why are there different turnaround times direct-to-branch? It's a question that needs to be asked."
The claims come as banks are labouring under a pile of mortgage deferral requests and home loans delayed by Covid-19.
Bank staff are struggling to process applications, leading to a deterioration in already-slow turnaround times.
ANZ, said to be among the slowest in the current market, recently reallocated branch staff to handle adviser applications. It has also bolstered its adviser processing team in recent weeks.
Have you noticed a difference in direct and adviser-led turnaround times? Please get in touch at firstname.lastname@example.org