Telephoned pledges of donations to Mexico City earthquake victims, made by dialing 976-9999 in area codes 213 and 415, were given a boost by the California Public Utilities Commission, which granted Pacific Bell's request that its normal profit on the calls be added to the contribution. Callers are charged $2 on their local phone bills. Of that, $1.50 goes to help Mexican earthquake victims through the Red Cross-Mexico Disaster Fund. Under the ruling, Pacific Bell will give up all but its 12-cent actual cost of handling a call to the fund, retroactive to Sept. 20. Phoned pledges total more than $86,000, officials said.