power going suddenly breakers and ELCB dose not drop what seems to be the issue?

ok guys i am sick of this and very puzzled. lately i have been having this power issue at home. funny thing is when i turn on some of the equipment at home like ac, fridge and all light the lights start to blink and then the power goes but comes back after 5 mins or 20. the circuits remain intact no issue from D board as well so i called the electric company they came and checked from the outside box and replaced a breaker but after they left when i turned everything on again the power is gone. so i called the electrical company again they did a research and replaced the power meter. before installing the meter they checked all wires power is ok after replacing meter again the power was gone but came back after 15 mins. i also ran a test to point the problem. i ran a 1 bulb test day with everything off. the bub starts to blink and power goes off. i dont know what seem to be the issue here do you guys think its a wire shortage or should i do a new wiring?