electrical showers

i have installed two electrical showers in a commercial environment, and put them on time lag switches so that they can be used for a set time, so not to be left on. due to inadequate water pressure i have installed a pump also, so that the pressure is better etc. basically what we have is:

two showers fed by the mains. normally the mains supply inside the shower feeds a switch on the front panel. this had been removed and the cable length increased with a different switch on the end allowing us to time the showers. from the other side of the switch (live when the switch is pressed) i have take a feed off to power an external motor. this is in turn connected to the pipes of the shower, increasing the pressure etc. the problem i have is; i have two showers, so replaced the wiring for both. from the switched live from the switch, take a feed off, and connected them into a connector block, thus feeding the motor.

my problem is that when one shower is turned on, the other comes on with it. obviously by taking the switched live and in effect joining them (by way of powering the motor) i have created a universal switch for both showers. what i need to figure out is exactly how i can wire from the switches (switched live) to the motor, individually.

any help would be great!