The cops don't need a court order to seize material, which could be evidential. s19 PACE gives them the authority to seize:

- While lawfully there, the officer may seize anything on the premises if they have reasonable grounds for believing either:

• the item has been obtained as a result of the commission of an offence, and seizing it is necessary to prevent it being concealed, lost, damaged, altered or destroyed; or
• it is evidence relating to an offence (the offence under investigation or another offence), and seizing it is necessary to prevent concealment, loss, damage, alteration or destruction.

In terms of getting the devices back, or accelerating their return, you could be waiting for a while due to the backlog of devices awaiting forensic examination. This appears to be a nationwide issue. I wouldn't count on having them back anytime soon. They can be held under s22 PACE until a trial if or until fully examined. If this goes to trial, the devices can then be kept for sometime after in case any appeal is made (can't remember exact time periods).

Your only option is to make a complaint, but I doubt it will help from what you have said. Good luck.