Hi, I have a circuit here which uses 105K capacitor (250V) for isolation of mains and resistance networked to finally provide 12V to 7805.
12V is maintained by using a Zener diode & 1Watt resistance of 6.8Ohm.

Problem:
The unit has to be installed where mains AC voltage can be from 150V AC - 260V AC @ 50Hz. The system hangs when it has to operate 4 relays at around 150V. It works perfectly with all 4 relays at 230V & above.

Because of limited knowledge in electronics, I am unable to decide what should I do or change in the circuit. All relays take their drive from 12V via 9013(npn) transistor with base connected to pic via 10K, and don't leave enough current for the PIC to operate at LOW voltage so the whole system hangs. It works fine when only 1 or 2 relays are operating at 150V.
Coil current for each relay is around 60mA.

I tried to increase the capacitor value from 105K to 155K, but my zener diode burned on OFF LOAD (when no relay is ON). I tried putting 3 1Watt 12V zener in parallel and they were still getting hot.

I am aware that there could be some complex calculations over current required for the circuit, based on that the capacitor value to choose & other specific components, hence I am here hoping to get an answer or an existing schematic with this kind of circuit. Any help in the right direction is much appreciated.