That would normally be the case with banks/insurance companies. You should also be aware that you bank is only offering you their product and you should shop around yourself, or employ a broker to set out the options.
That said, if you have a group of employees and 4 directors you could set up one scheme with 2 separate categories, one for directors, the other for the employees. If you want two separate schemes, then you could talk to other companies out there, for example the insurance companies, they may be willing to accept one 4 man executive scheme if a separate oridinary employee scheme is more than thier minimum.
On the 2 category route, each category can have it's own contribution rates etc. The Directors (if they are 5% or more directors) will still be allowed to take advantage of the wider range of retirement options, for example the ARF route.
Also, you need to be wary of the charging structure that will apply and if any commission will be payable. Also, you need to think about the admin end of things and how your bank's admin would stack up (online access for example). Also, Many of these institutions are willing to accept a cheque for the contributions each month as running it on a DDM can cause headaches from your end of things when it comes to reconciling things.